[QE-users] under pressure PbTaSe2 vc-relax calculation

[Amadeus]

Dear QE developer


I did the structural relaxation calculation for Pb at pressure of 3kbar， this is relax.in


&CONTROL
  prefix='PbTaSe2',
  calculation='vc-relax', pseudo_dir='../../', outdir='./tmp', verbosity='high',
  tprnfor=.true., tstress=.true., forc_conv_thr=1.0d-4, nstep=100,
/
&SYSTEM
  ibrav= 0, nat= 4, ntyp= 3, 
  occupations = 'smearing', smearing = 'gauss', degauss = 1.0d-2,
  ecutwfc = 50, ecutrho = 500,
/
&ELECTRONS
  conv_thr = 1.0d-8
  mixing_beta = 0.7d0
/
&IONS
/
&CELL
  cell_dynamics  = "bfgs"
  press          =  2.70000e+00
  press_conv_thr =0.1
/
ATOMIC_SPECIES
  Ta 180.9479 Ta.UPF
  Pb 207.2 Pb.UPF
  Se 78.96 Se.UPF
CELL_PARAMETERS (angstrom)
   3.4834700000  0.0000000000  0.0000000000
  -1.7417350000  3.0167735133  0.0000000000
   0.0000000000  0.0000000000  9.4755300000
ATOMIC_POSITIONS (crystal)
  Pb  0.0000000000  0.0000000000  0.0000000000
  Se  0.0000000000  0.0000000000  0.3246710000
  Ta  0.3333330000  0.6666670000  0.5000000000
  Se  0.0000000000  0.0000000000  0.6753290000
K_POINTS {automatic}
  15 15 5 0 0 0


In relax.in, press=3.0kbar. But after pw.x is done, relax.out show that total stress  (Ry/bohr**3)  (kbar)     P=-0.83, and This is inconsistent with press=3. this is part of relax.out


[rencong at mu01 phonon]$ grep 'Computing stress (Cartesian axis) and pressure' -A 15 relax.out


....


     Computing stress (Cartesian axis) and pressure


          total   stress  (Ry/bohr**3)                   (kbar)     P=        2.93
   0.00002030  -0.00000000   0.00000000            2.99       -0.00        0.00
  -0.00000000   0.00002030  -0.00000000           -0.00        2.99       -0.00
  -0.00000000   0.00000000   0.00001921           -0.00        0.00        2.83


     kinetic stress (kbar)  26877.23      0.00      0.00
                                0.00  26877.23     -0.00
                                0.00      0.00  26796.57


     local   stress (kbar)-103340.53      0.03      0.00
                                0.03-103340.50      0.00
                                0.00      0.00  89394.48


     nonloc. stress (kbar)   7797.15      0.00      0.00
--
     Computing stress (Cartesian axis) and pressure


          total   stress  (Ry/bohr**3)                   (kbar)     P=        2.96
   0.00002009  -0.00000000   0.00000000            2.96       -0.00        0.00
  -0.00000000   0.00002009  -0.00000000           -0.00        2.96       -0.00
   0.00000000  -0.00000000   0.00002028            0.00       -0.00        2.98


     kinetic stress (kbar)  26879.49      0.00      0.00
                                0.00  26879.49     -0.00
                                0.00     -0.00  26798.86


     local   stress (kbar)-103299.75      0.03      0.00
                                0.03-103299.72      0.00
                                0.00      0.00  89348.84


     nonloc. stress (kbar)   7797.79     -0.00      0.00
--
     Computing stress (Cartesian axis) and pressure


          total   stress  (Ry/bohr**3)                   (kbar)     P=       -0.83
  -0.00000653  -0.00000000  -0.00000000           -0.96       -0.00       -0.00
   0.00000000  -0.00000653   0.00000000            0.00       -0.96        0.00
   0.00000000   0.00000000  -0.00000384            0.00        0.00       -0.56


     kinetic stress (kbar)  26883.07      0.00     -0.00
                                0.00  26883.07     -0.00
                               -0.00     -0.00  26802.38


     local   stress (kbar)-103303.36      0.03      0.00
                                0.03-103303.33      0.00
                                0.00      0.00  89345.22


     nonloc. stress (kbar)   7795.83     -0.00      0.00
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